QC Flashcards
Basic principles that can help improve the efficiency of a department?
- budgets
- workflow
- inventory
- scheduling
- resources
What are capital budgets?
- for long term financing
- larger purchases such as major equipment or facilities
- things that aren’t consumed, depreciate over time
What is an operating budget?
- short term budget
- smaller purchases needed for day by day
- “consumables”
- usual based on the previous year
Who should monitor the supplies and materials?
Front line workers because we see it all
Factors that affect workflow in a department?
- staffing
- level of training
- organization of a department
- scheduling
- PM-preventative maintenance
- equipment
- team work
- communication
- weather
What does scheduling depend on?
- types of exams
- types of patients
- staffing
What is quality assurance?
Actions necessary to provide confidence that the x ray equipment and components produce diagnostic information of satisfactory quality with minimum doses to patients and staff
All encompassing management program used to ensure excellence in healthcare through the collection and evaluation of data
-optimal image quality
-accurate and timely diagnosis
-ALARA
A QA program examines what aspects of a facility?
All
- information quality
- clinical efficiency
- patient dose
What is the primary goal of a QA program?
Ensure accurate and timely diagnosis at the minimum dose to the patient and staff
“Enhancement of patient care”
4 major steps of establishing QC procedures?
- equipment must be functioning properly
- baseline performance values must be established
- reference test images must be available for comparison of QC
- result evaluation: acceptable limits and corrective actions must be determined
What is acceptance testing?
Process to verify compliance with the performance specs of the equipment
-results are used to set baseline values and acceptance limits on the operational performance of the equipment
Who performance acceptance tests?
Medical physicist
Purpose of a quality management program?
Control and minimize variables as much as possible
What variables is a quality management program controlling?
Human and equipment
- image receptor
- processing
- viewing conditions
- competency of staff
Quality is determined by what 3 factors?
- Expected quality
- Perceived quality
- Actual quality
What is expected quality?
- level of quality expected by the customer
- influenced by work of mouth (outside factors)
- we have the least amount of influence on this factor
What is perceived quality?
- based on customer’s perception of products/services (pt. experience)
- highly subjective
- hard to measure
- how well the staff perform responsibilities (greatest impact)
What is actual quality?
Statistical data measures outcomes and considered all factors that can influence the final outcome
Changes that affect DI departments?
- Advances in technology, equipment, and procedures
- Legislation and government regulations
- Accreditation Procedures
- Corporate buyouts and mergers
- Methods of reimbursement for services rendured
What is the cost of quality?
The expense of not doing things right the first time
What is quality assessment?
Measurement of the level of quality at some point in time with no effort to change or improve the level of care
What is is QC the same as QA?
No, its a component of QA
- deals with the technical aspects affecting imaging quality
- is a method of controlling images from start to finish
- ensures quality, repeatable results through the testing of equipment
3 levels of testing included in a quality management program?
- Non-invasive and simple
- Non-invasive and complex
- Invasive and complex
Non0-invasive and simple testing?
- performed by any tech
- simple test tools
- wire mesh test, spinning top test etc.
Non invasive and complex test?
- QC trained tech
- more sophisticated equipment
Invasive and complex testing?
- engineers/physicists
- take equipment apart
What is CQI?
Continuous quality improvement
-ensures and maintains quality, but also continually improves quality by focusing on improving the processes/system in which individual workers function rather than on individuals alone
What is output influenced by?
- supplier
- input
- action
Types of customers
- internal
- external
What are key process variables?
Components of any process that may affect the final output of the process
- manpower
- machines
- materials
- environment
- policies
Methods used to identify and analyze data
- Brainstorming
- Focus groups
- Quality improvement team
- Quality circles
- Multi-voting
- Consensus
- Work teams
- Problem solving teams
What is brainstorming?
Group process to develop a large bank of ideas
What are focus groups?
- small group focused on a specific problem
- can obtain additional info: surveys/interviews
- skilled facilitator required
What is a quality improvement team?
- group who implement ideas that focus group comes up with
- members of focus group: key customers, suppliers (pts and us)
What is a quality circle?
- group of supervisors/workers from same departments who share similar roles
- meet regularly to identify problems and form solutions
What is Multi-voting?
-used after brainstorming to filter out non-essential ideas and focus on realistic solutions, least votes get eliminated until 1 idea remains
What is consensus?
-after brainstorming, can decide on most important idea to be addressed
What are work teams?
- members are highly trained in their area
- empowered to take corrective action
- focus on solving a complete problem of task instead of just one step in the process
What are problem solving teams?
- work on specific tasks/problems
- identify, analyze, and solve quality and productivity issues
Which of the methods can be applied after brainstorming?
Focus groups, multi-voting, and consensus
What are the minimum requirements of a quality management program?
- equipment quality control
- administrative responsibilities
- risk management
- radiation safety program
What is an adverse indicator?
Undesirable, unanticipated event caused by medical management
What is a sentinel event indicator?
Unexpected occurrence involving death or serious injury or risk thereof
What is an aggregate event indicator?
Process or outcome related to many cases, desirable/undesirable
6 important administrative procedures of a total quality management program?
- Threshold of Acceptability
- Communication Network
- Patient comfort
- Personnel performance
- Record-keeping system
- Corrective action
What is risk management? Synonyms?
Identification, analysis, and evaluation of risks and the selection of the best methods for minimizing them
- safety and loss prevention
- total loss control
- loss control management
What is the purpose of a radiation safety protection program?
- ensure all employees are aware of their responsibilities to themselves and others
- must ensure patients, visitors, staff, and radiographers receive the minimum exposure possible
- create policies and procedures for safe handling of disposal of radioactive materials, accidents, and care of exposed patients
Classifications used by the FDA for medical devices
Class 1: General controls: less regulated, min potential for harm (lead apron, cassette)
Class 2: Special controls: general control not sufficient, special controls needed (collimators, contrast injectors)
Class 3: Premarket approval: most stringent, sustain/support human life (angioplasty catheters, guidewires, stents)
5 benefits of monitoring equipment?
- decreased downtime
- decreased dose to patient and techs
- decreased patient wait time
- decreased supply cost
- increased morale among staff
- increased rates of diagnosis
3 main components of a QC program?
- Visual inspection
- Environmental inspection
- Performance testing
What is a visual inspection? How often is is performed?
Includes checking the main components of the equipment
- safety
- proper function
- mechanical condition
- SHOULD be performed annually at minimum*
Components to inspect visually
- Control panel
- Overhead tube crane
- Radiographic table
- Lead apparel: annually, but every 6 months in preferable
- Miscellaneous equipment (sponges etc.)
What is an environmental inspection and how often should it be performed?
Primarily checking for mechanical and electrical safety
should be performed annually at minimum
Items included in an environmental inspection?
- High tension cables
- Tube tracks/counterweights
- Electrical safety
What is performance testing?
Evaluates the performance of the x-ray generator and tube using test tools
- QC tech or physicist perform these
- all tests besides the visual inspection fall into this category
What is a reproducibility test?
- Also known as repeatability test
- confirm the same mA, time and kVp will produce a consistent amount of radiation from exposure to exposure
- cannot be performed on a falling load generator
- annually, after any cals/repairs to generator or any reason to suspect malfunction
What is the acceptance criteria for the reproducibility test?
+/- 10%
Calculations for the reproducibility test? (4 steps)
- Calculate the mean mR, ms, and kVp for all 10 exposures
- Calculate the % difference between the mean and max value
(Max value-mean value)/mean value x 100 - Calculate the % difference between the mean and min value
(Min value-mean value)/mean value x 100 - Calculate the coefficient of variation of the 10 measurements of mR, ms, and kVp
How to calculate the coefficient of variation?
- Subtract each reading from the mean value
- Square each result and add them up
- Divide the result by 9
- Square root the result
- Divide the result by the mean value
* less than 0.05 = pass*
kVp accuracy test?
To confirm that the x-ray generator is producing the same kVp as indicated on the control panel
acceptance, annually, before/after generator service, or suspected malfunctioning
Calculations for kVp accuracy?
- Determine the difference between the set and measured kVp values
(Actual kVp - set kVp)/ set kVp x 100
kVp accuracy acceptable limits?
+/- 10%
What does linearity mean?
Sequential increases in the mA or mAs should produce the same sequential increase in the exposure measured
- reciprocity law*
- 70kVp @ 5 mAs = 20mR, 70kVp @ 10 mAs = 40mR*
mA linearity
- determine the output (mR/mAs)
- done on acceptance, annually, before/after generator service*
- after reproducibility, and kVp accuracy
mA linearity calculations
- Set mAs (mA x s)
- Average mR of 2 exposures at each mA station
- mR/mAs (divide average mR by mAs)
- Linearity
|x1 - x2| < 0.10(x1 + x2)
X1 = mR/mAs at mA station 1
X2 = mR/mAs at mA station 2
Timer accuracy
To confirm that the x-ray generator is producing an exposure for the amount of time set on the control panel
*acceptance, annually, before/after generator service, under/overexposed images, inconsistent EI values between similar exposures
Methods to test timer accuracy?
- Spinning top test tool: oldest, single phase unit only
- Wisconsin timing test tool/synchronous timer: 3 phase and HF gens, motor driven top @ 1rpm, creates 360 degree circle, exposure time = arc size in degrees/360
- Digital timing test tool: solid state detector, test tool displays exposure time
Timer accuracy calculations
To get the acceptable range:
0.1 x set time + 1 = ______ms
Set time + _______ = maximum limit
Set time - ________ = minimum limit
OR
Set ms +/- 10% +1 = acceptable range (+/- from set ms)
Leakage radiation?
To determine the amount of leakage radiation emitted in any direction from the focal spot of the x-ray tube
performed on completion of the room before equipment is put into service and should be checked when tube is replaced or housing is opened
Ways to perform a leakage radiation test?
- Paddle/radiation probe: most common
2. Cassette method: surround the x-ray tube with cassettes with collimators closed
% leakage formula
(Leakage mR / primary mR) x 100
Acceptable limits for leakage radiation?
Should not exceed and air kerma of 1.0mGy/hr or 115mR @ 1m from focal spot
Lead apparel testing
- to determine if any cracks/holes are present and if the lead apparel is safe for usage
- performed with new lead apparel or annually (every 6 months preferred)
- consider size/location of defect if any
AEC reproducibility
To confirm that the exposure is being terminated at the proper time after a predetermined quantity of radiation had been detected, thereby producing the same output from exposure to exposure when mA and kVp remain the same (if not images will be consistently over/under exposed)
- AEC controls time
- testing done on acceptance, annually, whenever service to AEC done, or when there is an indication of malfunction
Calculations for AEC reproducibility
%variation = (mRmax - mRmin) / (mRmax + mRmin) x 100
%variation = (msmax - msmin) / (msmax + msmin) x 100
Acceptable range to AEC reproducibility?
Equal to or less than 20% = PASS
AEC uniformity/field balance
- to ensure that any combo of AEC cells activated will terminate at the appropriate time when the same kVp, mA, and part thickness are used
- performed annually, when AEC is malfunctioning, or when it has been serviced
- less than 20% variance = pass (SC35 manufacturer specs)
Calculations for AEC uniformity/field balance?
%difference = ((measured - mean) / mean )x 100
Do for ms and mR
AEC density control
- to confirm that the exposure is being terminated at the proper time when using density control settings and the same kVp and mA
- performed annually, when AEC serviced or malfunctioning
- 15-25% difference = pass (SC35 says manufacturer specs)
Calculations for AEC density control
%difference = ((1st setting - 2nd setting) / 2nd setting) x 100
Ex. (-2 setting - -1 setting) / (-1 setting) x 100
Do for mA and mR
AEC sensitivity - Test 11
- to confirm that the exposure is being terminated at the proper time when using different speed/sensitivity settings and the same kVp and part thickness
- performed annually, when the AEC has been service or is malfunctioning
- Manufacturer specs = pass
- double speed = half exposure
- half speed = double exposure
AEC sensitivity calculations?
% variation = ((S1-S2) / S2)x100
*use S400 as a comparison point
Automatic Collimation (PBL)-Test 12
- to confirm that the PBL quickly and accurately adjusts to the appropriate field size required
- performed SEMI ANNUALLY, before/after work is done on x-ray tube, collimator, or bulb
- Within 5seconds = pass
- length and width differences = within 3% of SID = pass
- sum of length and width actual vs IR = within 4% of SID = pass
Steps to calculate for PBL
- Measure length and width of image
- Determine magnification factor
- Multiply width and length by magnification factor
- Calculate 3 and 4% of the SID
- Calculate the difference between the cassette size and the actual beam
- Compare length and width to 3% SID acceptance criteria
- Compare sum of actual vs field size width and length. Compare to 4% SID acceptance criteria
Calculations for PBL?
MF = SID/SOD SOD = SID-OID
Collimator light/x-ray field congruency and perpendicularity-Test 13
- to confirm the congruency of the light and x-ray field to ensure that the central ray is perpendicular to the IR
- done on acceptance, annually (semi-annually?), after any service, or suspect misalignment
- sum of distance to opposite sides of IR = within 2% of SID = pass
- circles within 3 degrees = pass
Calculations for collimator/x-ray field congruence
- SID x 2%
- A+C = _____
B+D = _______
What is a half value layer?
The amount of filtration needed to half the energy of the x-ray beam from its original value
What is total filtration?
Added and inherent together
Half value layer test - test 14
- to confirm that the permanently installed filtration in the x-ray tube meets the minimum standard to minimize patient radiation dose
- done on acceptance, annually, when the tube is replaced, when collimator removed, or any changed to added filtration
- see SC 35 table for acceptance for each kVp settings
Steps for HVL test
- Plot results on graph
- Draw best fit line
- Calculate 50% of exposure with no filtration (___mR @ 0mm AL / 2) and draw a horizontal line on the graph at this point
- Where the two lines intersect is the HVL-follow line down to determine amount of filtration
Fluoroscopic kVp accuracy?
To confirm that the fluoro x ray generator is producing the same kVp as that which is indicated on the control panel
done upon acceptance, and tested annually
-determine the % difference
+/- 10% = pass
Calc for fluoro kVp accuracy?
% difference = actual kVp - set kVp / set kVp x 100
Max fluoroscopic exposure rate?
To confirm that the max exposure rate that can be delivered does no surpass the regulations as determined by the SC35 for any combo of mA and kVp
- under table unit = rate at tabletop
- over table unit = rate where beam enters patient
Max fluoro exposure rates according to the SC35
-Equipment without automatic intensity control:
50mGy/min or 5.75R/min
-Equipment with automatic intensity control:
100mGy/min or 11.45R/min
-Equipment with an automatic intensity control and high radiation control activated
150mGy/min or 17.18R/min
Fluoroscopic field size and beam alignment?q
To confirm the congruency of the light and x-ray field and that the central ray is perpendicular to the image intensifier
- actual light vs light field size must be less than 2% of the SID
- within 3 degrees of the perpendicular to the IR plane
Fluoroscopic resolution?
To determine if the resolution is within acceptable limits
- test is subjective
- annually or when any mods have been made*
Acceptable limits for fluoroscopic resolution?
-minimum 1.21lp/mm with a 23cm field
-minimum 1.61lp/mm with a 15 cm field
(SC35 says go by manufacturer specs)
Fluoroscopic low contrast resolution?
To determine that the low contrast resolution is within acceptable limits
- test is subjective
- performed annually or when any mods have been made*
What is low contrast resolution?
Ability to resolve relatively large structured with a small difference in radiolucency
Fluoro low contrast resolution acceptable limits?
-minimum 2 largest holes (7mm and 5mm) with 2Al blocks
SC35 says manufacturer specs
What is high contrast resolution?
The ability to resolve small, thin areas with a large difference in radiolucency
Fluoroscopic high contrast resolution?
To determine the high contrast resolution is in acceptable limits
- test is subjective
- performed annually or when mods have been made*
Fluoro high contrast resolution acceptable limits?
-input screen 23cm:
Minimum 20 at the edge and 20-24 at the center with 2Al blocks
(SC35 says manufacturer specs)
Fluoroscopic image noise/lag?
To determine if the image lag and noise displayed on the monitor is within acceptable limits
- test is subjective
- observer must have experience good and poor systems to have a basis of comparison
- observer moved objects under fluoro
- must be noted what type of camera (vidicon/plumbicon)
- tested annually or when mods have been made*
- observe a rotating test tool as per the SC35: visualize wire 0.013” or smaller
Difference in image lag between and vidicon and a plumbicon?
Vidicon: more lag
Plumbicon: less lag
Types of noise
- electronic
- quantum mottle
3 levels of system performance for QC and system maintenance?
- routine: Q/C tech
- full inspection: physicist
- system adjustment: vendor service personnel
What may reduce image quality on a CR and DR imaging plate?
-dust, dirt, scratches, cracks
What kind of cleaner cannot be used on an IP?
Water based, also do not poor directly on IP as it may stain
IPs need to be inspected for?
- hairline cracks
- dirt
- debris
- defects
The inside of the cassette should not come in contact with?
Soap and water as soap may leave residue
Frequency of cleaning of IPs and IRs is dependent on?
- patient volume
- plate handling
- how often artifacts are noticed
- general recommendation is weekly visual inspection for dust dirt and monthly cleaning of IPs
Which type of monitor attracts more dirt? Why?
CRT because of electrostatic attraction
Potential issues with CRT monitors?
- can lose focus over time
- lose image brightness and contrast
- less variation in quality than with LCD
When comparing variability of digital image display quality, what is the weakest link?
CRT monitors
Potential issues that may occur with LCD monitors?
- limited viewing angles
- requires replacement of light source (approx. over 3000 hrs)
Tests that can be done with a phantom?
- relative sensitivity
- shading/uniformity
- contrast evaluation
- spatial accuracy
- laser jitter test
- image noise test
- erasure test
- accuracy of measurement tools
- system linear test
If phantom is unavailable, what tests can be done with other methods?
- uniformity
- spatial accuracy
- erasure test
- laser function
- wireless transmission integrity (wireless DR systems)
Relative sensitivity test
-when the same exposure is taken, the CR/DR system should display a consistent exposure indicator
Shading or uniformity test?
- evaluation to ensure the brightness is uniform across the entire IR
- also confirms the CR readers light guide position, if the laser is not performing uniformly, low contrast light and dark bands may appear
Laser jitter test?
-evaluates the horizontal and vertical movement of the laser optic and transport systems of the CR reader and printer
Image noise test
-evaluates the image for noise and artifacts and monitor degredation
System linearity is important for what?
-patient dose
What is system linearity?
-if exposures are increases in 10% increments of mR, the exposure indicator should track accordingly
Spatial accuracy test: if distortions appear across multiple plates, the likely cause is what?
The laser in the CR reader, not the plate
Laser function test
Expose ruler, edges should appear as straight lines
